In general, a Constant Velocity Joint (CVJ) is a device that enables a drive shaft to transmit power at constant velocity and at various angles. The constant velocity joint is generally used for front wheel drive cars or all-wheel drive cars.
FIG. 1 is a view showing a common constant velocity joint. Referring to FIG. 1, a common constant velocity joint includes a constant velocity joint housing 100 having guide grooves 110 on the inner side, a spider 200 disposed in the constant velocity joint housing 100, combined with a shaft 300, and having a spider journal 202, spherical rollers 400 disposed in the guide grooves 110 of the constant velocity joint housing 100, and needle bearings 500 disposed between the spherical rollers 400 and the spider journals 202.
Further, a striker 600 and a circlip 700 are disposed on the spider journal 202 to prevent separation of the needle bearings 500.
Power outputted from an engine (not shown) is transmitted to the housing 100 and then transmitted to a wheel (not shown) through the spherical rollers 400, the spider 200, and the shaft 300.
Even if the phase of the wheel changes, depending on the traveling conditions of a vehicle, the spherical rollers 400 move along the guide grooves 110, such that the connection angle between the shaft 300 and the housing 100 changes and the power from the engine is smoothly transmitted to the wheel.
However, there are about thirty needle bearings needed for one set of rollers, each constant velocity joint needing three sets of rollers, and two constant velocity joints are usually needed for a front wheel drive car, such that about one hundred eighty needle bearings are needed.
Further, burden on cost is high, because many parts require grinding. Grinding is added after turning to reduce friction force on the contact surfaces of the parts, and precise grinding is required for the inner side of the spherical rollers 400 and the outer side of the spider journals 202 which are in contact with the needle bearings 500. Noise, vibration, and harshness (NVH) characteristic is poor due to many friction surfaces, where friction is generated on the surfaces between the needle bearings 500, the spherical rollers 400, and the spider journals 202, and between the needle bearings 500.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.